Consequences of propagule dispersal and river fragmentation for riparian plant community diversity and turnover
The spatial distribution and temporal availability of propagules fundamentallyconstrain plant community development. This study experimentally tested several hypothesesabout the relative roles of wind and water dispersal in colonization and development ofriparian communities along rivers. Through co...
| Published in: | Ecological Monographs |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Umeå universitet, Institutionen för ekologi, miljö och geovetenskap
2010
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| Subjects: | |
| Online Access: | http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-37059 https://doi.org/10.1890/09-1533.1 |
| Summary: | The spatial distribution and temporal availability of propagules fundamentallyconstrain plant community development. This study experimentally tested several hypothesesabout the relative roles of wind and water dispersal in colonization and development ofriparian communities along rivers. Through controlling the source of propagules (dispersed bywind, water, or both) reaching newly created, bare river margin sites, we isolated the relativeroles of dispersal and other factors in plant community development over five years.Replicated treatments were established at 12 sites spanning 400 km along two adjacent riversin northern Sweden, one fragmented by a series of dams, the other free-flowing. Bare rivermargins receiving only water-dispersed propagules had significantly higher species richnesscompared to plots receiving only wind-dispersed propagules during the initial two years ofcolonization. Species richness increased annually throughout the study along tranquil andturbulent reaches of the free-flowing river but reached an asymptote at comparatively lowrichness after a single year on the impounded river. Propagule source strongly influencedspecies richness during the initial establishment along both rivers, with richness beingsignificantly higher in plots receiving water-dispersed seeds. This strong treatment effectcontinued to be important through time along the regulated river but diminished inimportance along the free-flowing river where other factors such as soil moisture, lightavailability, and exposure of sites to fluvial disturbance overshadowed the influence ofdispersal pathway in mediating species richness. This suggests that hydrochory (plantdispersal by water) may be more important for maintenance of diversity in regulated systemswhere long-distance dispersal is absent or negligible, but that the rich local propagule sourcealong free-flowing rivers supports high species richness. The number of unique species washigher in water-dispersal plots along both the regulated and free-flowing rivers. This ... |
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